1969 435HP auto transmission pan

[Jeff D.]

Is this the correct transmission pan for my 1969 435HP auto? If so, it appears to be painted with a light gray paint. Is that correct or did someone do that to it in the past? Thanks, Jeff

[Terry M.]

Re: 1969 435HP auto transmission pan

Yes that appears to be the correct configuration although a side view, or closer to a side view would be helpful. Original finish was a light gray plate that I think is tin plate, but others may have a different opinion. It definitely was not originally painted.

[Richard M.]

Re: 1969 435HP auto transmission pan

Also the vacuum modulator assembly should be painted black. Richard

[Chuck G.]

Re: 1969 435HP auto transmission pan

Is this the correct transmission pan for my 1969 435HP auto? If so, it appears to be painted with a light gray paint. Is that correct or did someone do that to it in the past? Thanks, Jeff

I'm not so sure that it should have the Hydromatic embossings. I thought originals were perfectly smooth....no embossments.

Chuck

[Chuck G.]

Re: 1969 435HP auto transmission pan

Smooth like this.....

Chuck

[Greg L.]

Re: 1969 435HP auto transmission pan

I think Chuck is correct. I think the "Hydramatic Div of GMC" came much later and was a later service replacement pan.

[Jeffrey S.]

Re: 1969 435HP auto transmission pan

Chuck,Do you know if this is the original vacuum modulator or a replacement? Although my car is a small block, the pan is exactly as yours is and it is original to the car. Attached is a photo of the pan from my '69
Jeff

[Ralph S.]

Re: 1969 435HP auto transmission pan

My L/71 M/40 VIN 38161 Built 12/11/69 has a smooth pan with 2 dimples and a metal flywheel cover unlike the plastic one in Chuck's photo

[Terry M.]

Re: 1969 435HP auto transmission pan

My L/71 M/40 VIN 38161 Built 12/11/69 has a smooth pan with 2 dimples and a metal flywheel cover unlike the plastic one in Chuck's photo

I guess I have learned something from you guys today. Thanks.

What about the vacuum modulator? I remember one of the TH400s I had used a larger black can, but that may have been the 1967 GMH 3/4-ton pick-m-up.

[Chuck G.]

Re: 1969 435HP auto transmission pan

Chuck,Do you know if this is the original vacuum modulator or a replacement? Although my car is a small block, the pan is exactly as yours is and it is original to the car. Attached is a photo of the pan from my '69
Jeff

I cannot answer. I don't know about the vacuum modulator.

I am 99% sure I'm correct about the pan, however.

Chuck

[Michael H.]

Re: 1969 435HP auto transmission pan

I guess I have learned something from you guys today. Thanks.

What about the vacuum modulator? I remember one of the TH400s I had used a larger black can, but that may have been the 1967 GMH 3/4-ton pick-m-up.

Terry

I'm pretty sure that the large black modulator was used for all TH-400 transmissions from 65 to at least 1969. Possibly later.

[Chuck G.]

Re: 1969 435HP auto transmission pan

My L/71 M/40 VIN 38161 Built 12/11/69 has a smooth pan with 2 dimples and a metal flywheel cover unlike the plastic one in Chuck's photo

Don't know about the plastic vs. metal flywheel cover either, Ralph.

I can say that my 69 was judged many times, at both Regionals and Nationals, and nobody mentioned anything about the pan or flywheel cover. That being said, in all honesty, those would be tough to see laying on the floor judging a chassis.

Chuck

[Terry M.]

Re: 1969 435HP auto transmission pan

Terry

I'm pretty sure that the big black modulator was used for all TH-400 transmissions from 65 to at least 1969. Possibly later.

My memory is that sucker had a date code stamped into it too.

On the other hand the point Chuck makes about some of these details being hard to see is valid; but the TH stamping on the bottom of the pan should be a no brainer.

[Joe L.]

Re: 1969 435HP auto transmission pan

Terry

I'm pretty sure that the large black modulator was used for all TH-400 transmissions from 65 to at least 1969. Possibly later.

Michael-----


Yes, the 1965-70 modulator valve (of course, just 68-70 for Corvettes), GM #8625976, was painted black. The 71-72 valve, GM #3963812, which also replaced the 8625976 for SERVICE in July, 1970, I believe was also black painted. The 73-75 valve, GM #3027222 which also replaced the earlier year model valves for SERVICE in September, 1972 was also black-painted.

In December, 1988 the 3027222 was discontinued and replaced by GM #8629941. I don't know if this valve was painted, or not. It was discontinued without supercession in September, 2000.

Of course, the valves supercessive to the 8625976 were configured slightly different than the 8625976


A valve is available from GM or Delco today, though. I don't know if it's OEM-quality, or not, since it does not trace its lineage to the OEM valves. It's GM #89057785.

[Joe L.]

Re: 1969 435HP auto transmission pan

Don't know about the plastic vs. metal flywheel cover either, Ralph.

I can say that my 69 was judged many times, at both Regionals and Nationals, and nobody mentioned anything about the pan or flywheel cover. That being said, in all honesty, those would be tough to see laying on the floor judging a chassis.

Chuck

Chuck-----

The original 1968-69 Corvette THM-400 converter underpan was GM #3868810. It was definitely of stamped steel construction. That underpan is still available today under the original part number. Is it still metal? I don't know but it would be unusual for a part to change from metal to plastic without a part number change. It is possible, though. In any event, stamped steel reproductions are available and the used market ought to have PLENTY of these available. They were also used on THM-400-equipped passenger cars from 1965 to 1969. 1970 and later are different, though.